Machine-tool control



W. F. MAYER.

MACHINE TOOL CONTROL.

APPLICATION HLED JUNE 21. 1919.

Patented sept. 14,1920.

. /NvE/vToR ATTORNEY UNITED vsTA'rlas PATENT oFF-ICE.

WALDEMAR F. MAYEB, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T TAYLOR-WHARTON IRON AND'STEEL COMPANY, 0F HIGH BRIDGE, NEW- JERSEY, A.

PORATION 0F NEW JERSEY.

con-

MACHINE-Toor. CONTROL. y

n a citizen of Switzerland, residing at Phila /trate them.

delphia, in the county of Philadelphia and State of Pennsylvania, haveinvented certain new and useful Improvements in Machine-Tool Control, ofwhich the following is a specificaton.

- The principal objects are to provide for operating and controllingmachine tools, such as lathes, boring mills, milling machines, and thelike, by means of fluid gears or so-called hydraulic transmissions; to

, prevent 'overloading of the prime mover,

usually an electric motor; to provide for limiting the tool pressure soas not to spoil the tool; and to control the speed within or below thelimits determined by these requirements.

With such .and other objects in View, the nature, characteristicfeatures and scope of the invention will more readily be understood fromthe following descripton taken in connection with the accompanyingdrawin s, forming a part hereof, whereinigure 1 is a side elevationalview, partly in section, of the headstock portion of a roll' latheembodying my invention.

Fig. 2 is a vlew principally in section of control members of thehydraulic transmission.

Fig. 3 is a sectionon line 3-3 of Fig.- 2.

In the illustrated embodiment of my invention applied to a roll lathe, 1designates the face plate supported on a spindle 2 and having aninternal gear 3, which meshes with a pinion 4. The latter is keyed tothe driving shaft` of a hydraulic engine 5, which is driven in the wellknown manner by fluid ressure supplied by a reversible variable uiddelivery pump 6. The fluid supply and return. connections are indicated,respectively, at 7 and 8. The pump is driven preferably at constantspeed in any` suitable manner, for example, by an electric motor 9, acoupling being indicated atv 10. In lieu of the coupling, a ear orclutch connection may be em loye are of well known and) usualconstruction it has not been deemed necessaryw to illus- Specificationof Letters Patent.

and as theyl The electric motor or other primev mover, pump, hydraulicengine, and face plate spindle are supported or carried by a casting 11,which is bolted onto a bed-plate 12. The casting 11 alsosupports aspring-loaded adjustable safety valve 13 located in the llid linebetween the pressure and discharge s1 es.

The rate of delivery of the pump is positively controlled by a lever 14,and since the speed of the hydraulic engine depends upon the rate offluid flow through the pump and engine, the position of lever 14determines one certain lathe speed.

The differential valve 13 is mounted in a housinvl 16 and normallyseparates the Working luld passages .7 and 8. The valve stem 17 isequipped with spring washers 18, one of which bears against a shoulderedportion of the stem, and the other against an adjusting member or nut19. The compression Patented Sept. 14, 1920. Application led .Tune 27,1919. Se'rial No. 307,161. y

spring 20 between the washers is capable and a cap-plate 23, whichengages the nut.

The housing 16 and the valve-stem 17 have the same number ofscrew-threads per inch so that the parts can be-adjusted with precision,and the spindle 17 is secured against rotation, to admit of saidadjustment, by means of a slotl 24 and key 25.

The movement of speed control lever 14 is limited4 in one' direction bya chain 26, one end of which is fastened to the lever, as at 27, and theother end of which is connected to a loose ring or swivel 28 on the ca21. y

lince an electric motor or any other prime mover has a limited powercapacity, it is essential for efficient operation that the variablehydraulic speed gear shouldbe of such design that it will offer moreresistance than the rime mover can overcome.

T e power of the hydraulic engine is thef susl product of its torque,determined by fluid pressure, and of its angular speed, determined bythe position of the control lever 14. Therefore, speed and pressure haveto be cordinated for constant horsepower out- I put. It is evident thatfor high fluid presthrough a channel 32, so that the' differential`valve is under pressure from opposite directions. The variance 1npressure as between the two disks is transmitted to the spring.

20, which has a certain initial compression set by. the'hand-wheel 22.If the resultant valve pressure exceeds the initial spring compressionthe valve will move outward and continue to compress the spring untilpassage 30 is in communication with ,passagex 33,- the effect of whichis to by-pass fluid from the pressure side 7 to the discharge side 8 andto stop the hydraulic engine and consequently the face-plate. Thepressure cannot increase while the safetyvalve is bypassing fluid.Hence, a constant predetermined tool pressure exists andA no harm canbefall the tool. L

The speed is determined by the-position of the control lever 14.Referring to Fig. 2, the solid line illustration of the levercorresponds to a certain predetermined cutting speed position. Thedotted line illustration 141 indicates zero speed (stop) and theillustratio-n 142 indicates reverse speed. The rate of speed increasesgradually from zero speed position l141 as the lever is moved fartherand farther away from that position. The by-pass pressure increasesgradually as the spring 20 is compressed gradually by the hand-wheel 22.

The lever restraining element or chain 26 will not permit excessivespeed even though the by-pass pressure is adjusted fora high value,because the stretched position of the chain always corresponds to themaximum transmitted horsepower. Hence, the chain acts as a safeguard toprevent overloading of the prime mover.

`The adjustment of the spring 2O depends upon the nature of the tool andthe diameter yof the work.

The fluid pressure being proportional to torque, which in turn dependson tool pressure and diameter ofl work, these values should bedetermined by practice and tabulated for use as a guide to theoperative.

With the by-pass pressure adjusted to protect the tool, the operator mayrunv the lathe within the speed limit which corresponds to that pressureat the maximum horsepower.

Having described the nature and objectsv of the invention, I claim l. Amachine tool control, comprising the combination of a member adaptedv tobe driven at different speeds, fluid IIlGLIlS fOr and face plate, andmeans inter-related with the fluid gear for limiting the tool pres sureand for controlling the speed.

4. A roll lathe control, comprising thecombination of a face plate, aprime mover, a hydraulic transmission interposed between the prime moverand face plate and comprising a reversible variable fluid deliverypump,(a hydraulic engine, and their complemental fluid connections, andmeans for controlling the delivery of the pump.'

5. A roll lathe control, comprising the combination of a face plate, aprime mover, a hydraulic transmission interposed between the prime moverand face plate and comprising a reversible variable fluid delivery y,pump, a hydraulic engine, and their complemental fluid connections,means for controlling the delivery of the pump, and a limit device forsaid means.

6. A roll lathe control, comprising the combination of a face plate, aprime mover, a hydraulic transmission interposed between the prime moverand face plate and comprising a variable and reversible fluid delliverypump, a hydraulic engine, and their complemental fluid connections, andmeans for controlling the delivery ofthe pump 'and having an initialpredetermined cutting s ee 7. A roll lathe control, comprising thecombination of a face plate, a prime mover, a hydraulic transmissionoperatively connecting the prime mover and face plate and comprising avariable and reversible fluid delivery pump, a hydraulic engine, andtheir complemental fluid connections, and means for controllin thedelivery of the pump and movable rom apredetermined cutting speeposition through zero speed to reverse spee j 8. yA roll llathe control,comprising the combination of a face plate, a prime `mover,

a hydraulic transmission operatively connecting` the prime mover andface plate and comprising a variable and reversible fluid delivery pump,a hydraulic engine, and their complemental fluid connections, and

means for controlling the delivery of thel pump and movable from apredetermined cutting speed position through zero speed to reverse speedand the extreme position of Which corresponds to the maximum transmittedhorsepower. i

9. A roll 4lathe control, comprising the combination of a face' plate, aprime mover, a hydraulic transmission operatively com necting theprime'mover and face plate and comprising a variable and reversibleliuid delivery pump, a hydraulic engine, and

their complemental fluid connections, a safety valve in the fluid line,and means for controlling the delivery of the pump Within the limitsfixed by said valve.

l0. A roll lathe control, lcomprising the combination of a face plate, aprime mover,

a hydraulic transmission operatively connecting the prime mover and faceplate and comprising a variable and reversible 11. A roll lathe control,comprising the combination of a face plate, a prime mover, a hydraulictransmission operatively connecting the prime mover and face plate andcomprising a variable and' reversible fluid delivery pump, a hydraulicengine, and their complemental fluid connections, a safety valve in thefluid line, means for controllinfg the delivery of the pump within thelimits fixed by said valve, and a checkon said means independent of thevalve. f

In testimon whereof I affix m si ature.

ALDEMAR F. gER.

